Modern redistributive welfare states have been mainly enacted by left party governments. Recent theoretical models link electoral behaviour and government formation dynamics by taking into account the impact of electoral systems. Some authors have argued that cross-class coalitions tend to form left-wing and more redistributive governments under proportional representation systems and right-wing, less redistributive governments, in majoritarian systems. According to these models, PR leads to a systematic and long term overrepresentation of left parties in government and allows implementing redistributive welfare states. In our paper, we investigate the effects of electoral systems on the ideological composition of governments in modern parliamentary democracies. We aim to explain why we find a higher number of left party governments in Scandinavian welfare states than in Anglo-Saxon countries. We test several hypotheses why countries with proportional representation are more often governed by left parties than countries with majoritarian electoral systems and untangle the relationship between electoral systems, party systems and long term patterns of government formation. To test existing hypotheses, we draw on a new data set about the party-political composition of parliaments and governments (www.parlgov.org) and use different sources for party positions in the political space. In the study, we cover the whole post-war period and most OECD democracies.
